Process for determining the com



AS MIXTURE J. A. STEIN PROCESS FOR DETERMINING THEV'COMBUSTIBLE CONTENTIN A G 3 9 l L 2 y m J Original Filed March 19,1952

INVENTOR. 14 6 72/ BY V ATTORNEY Reissued July 21, 1936 Re.

UNITED STATES PATENT OFFICE PROCESS FOR DETERMINING THE COM- ggS'fgIBLECONTENT IN A GAS MIX- Joseph A. Stein, Pittsburgh, Pa., assignor toBacharach Industrial Instrument Company, a corporation of PennsylvaniaOriginal No. 1,940,513, dated December 19, 1933, Serial No. 600,044,March 19, 1932. Application for reissue April 11, 1936, Serial No.13,978

2 Claims. (01. 23-232) The invention relates to a process formeasurcatalyzing wire occurs under any condition of ing the combustiblecontent of a gas. Ordinarily use. The range of use of the apparatus isthus the gas to be tested is a gas of combustion in greatly broadenedand the cost of operation due order to determine the completeness ofcombusto replacements reduced to a minimum. 5 tion in the apparatus inwhich the gas is con- Briefly stated, this result is secured by dilut- 5sumed, but the invention is applicable to the ing the gas measured witha volume of air which measurement of gases other than gases of combearsa definite relation to the volume of gas used, bustion. The apparatusemployed in the pracand which will guard the apparatus against failticeof the process is of the general type shown ure of the catalyzing wireregardless of changes in the patent to Max MoellerNo. 1,562,243, whereinthe composition of the gas whose percentage 10 in the temperature of acatalyzing wire as afof combustible is under determination. One formected by the gas burned adjacent the wire is of apparatus suitable forcarrying out the procused as the determining factor in ascertaining essis shown in the accompanying drawing, the percentage of combustible(gas) in the gas wherein: tested. Apparatus of this type has been usedThe figure is a diagrammatic view partially in 15 with some success inmeasuring the 00,112 and section. other combustibles in which the amountof com- The construction involves the use of a Wheatbustible is low,that is not over 4 to 8 per cent stone bridge arrangement in which I and2 are of the gas tested, but serious difficulties have atstandardresistances and 3 and 4 are a pair of retended the use of the apparatuswhen the comsistance wires located in the chambers or tubes 5 20bustible content exceeds these percentages, and E. The resistance wiresare preferably made which it is the purpose of the present invention ofplatinum alloy although any other suitable to overcome. One of the maindifficulties is the alloy may be used which will act as a catalyzingfact that the apparatus has been unreliable, due agent when exposed tocontact with gases of comto the temporary or permanent failure of thebustion and oxygen. The gases to be measured 25 catalyzing wire tofunction under varying conare caused to pass through the chamber 5 whileditions. A condition referred to as poisoning or the chamber 5 containsatmospheric air, the two contamination of the catalyzing wire ariseswhen wires which are of the same material, length and the combustible inthe gas increases above a cercross section thus serving as a basis ofcomparison tain point. At such time the catalysis may fail as is wellknown in the art. 30 so that the device ceases to record or indicate Thepoints I and 8 are connected by the wires at all. In other cases, thedevice continues to 9 and Ill forming a circuit in which is locatedindicate the percentage of combustible, but does an indicatinginstrument, such as the galvanomso incorrectly. This failure isordinarily merely eter ll. Operating current is supplied from atemporary and is remedied when the combustible battery l2 in the circuitl3, l4 and this circuit is 35 content decreases below a certain point,but in provided with a small variable resistance l5 and some cases itbecomes permanent and. a new the ammeter l5a for the purpose ofadjustment. catalyzing wire has to be substituted. The reli- The gas ofcombustion to be analyzed is conability of the device is also impairedwhen the ducted to and from the tubular chamber 5 by the catalyzing wireis overheated due to catalytic pipes 16 and ll, of which I6 is the inletand I1 40 combustion of high percentages of combustible the outlet, theinlet pipe being provided with the gas which is entirely apart from thefailure of the orifice member I8. Connected to the gas inlet wire due topoisoning. These liabilities to failure pipe I6 is an air inlet pipe i9whose outer end have greatly retarded the introduction and use isprovided with a cavity having a cotton filter of the apparatus, which inother respects,both as 20 therein. Admission of air to the cavity is 45to cost and ease of use, is admirably adapted for afforded by theopening 2|, and the orifice memtesting gases. ber 22 regulates the flowto the pipe Hi. The My invention overcomes the difliculty above filter20 protects the pipe and its orifice from outlined, making the apparatusentirely reliable clogging with dirt. under any condition of use, sothat no poisoning The current supplied to the wires 3 and 4 is 50 of thewire will occur or overheating thereof. such as to heat them to a pointwhere the wire 3 The process may be employed for accurately will ignitethe combustible in the stream of gas determining the combustible, whensuch comby catalysis. The resulting combustion raises bustible rangesfrom 0 to 100 per cent of the gas the temperature of the wire 3 stillfurther, wheretested, and no poisoning or overheating of the by theresistance of the latter is increased by an 55 amount proportional tothe heating efiect of the combustible contained in the gas being tested.The change in resistance of the wire unbalances the circuit of theWheatstone bridge, of which the catalyzing wire, as heretoforeexplained.

I have discovered that the range of the apparatus may be increased toany desired extent, without shortening its life, by a proper dilutionwidely varying conditions of combustible content must be very great,preferably in the neighborhood of twelve volumes of air to one of gas.

Stated difierently, the volume of air should be such that with a maximumin which the combustible never ranges over 16 per cent, the volume ofair to that of gas may range as low as 2 to 1. In the particular siredorifice 22 being about l2 times the cross sectional area of the orificeID. The volume of diluting air thus provided not only pretheparticushown, the relative volumes of air and gas are governed by thesize of the orifices ner rather than by the size of the orifice.

The apparatus will ordinarily be calibrated to indicate the percentageof CO and H2 or a combination of the two, but may be calibrated toindicate the percentage of any other combustible as.

What I claim is:

1. In a process of gauging the combustible conich has for any type ofgas being least twice. the

JOSEPH A. STEIN.

